N = gets.to_i
w_list = gets.chomp.split.map(&:to_i)
half = 0
dp = Array.new(100, Array.new(10001, true))

def solve(idx, total)
  return false if idx >= N || total > half
  return dp[idx][total] if dp[idx][total] == false

  return true if total == half

  return true if solve(idx + 1, total) || solve(idx + 1, total + w_list[idx])
  return dp[idx][total] = false
end

def main
  total = w_list.inject(:+)

  return "impossible" if total & 1 == 1

  half = total >> 1
  w_list.sort!

  return solve(0, 0) ? "possible" : "impossible"
end

puts main()